Multiple prognostic factors can affect the survival outcome of cancer patients, while a single prognostic factor can not fully predict the individual survival. In the light of the scarcity and differences in fibrosarcoma cases, assessing clinical prognosis outcomes can be very challenging. Relying on the traditional AJCC staging system as before has not been sufficient to accurately guide treatment and assess the prognosis of cancer. Nomogram is a graphical illustration of a statistical model for calculating the cumulative effect of several variables and can be used to predict individual survival outcomes. Nomograms have been established for a variety of cancers and have shown a more accurate in predicting prognosis than traditional tools (Liang W et al., 2015; Wang Y et al., 2013; Wu S et al., 2018; Ma T et al., 2019; Zhang L et al., 2019; Zhang SL et al., 2019). As far as we know, the present study is the first article to develop and validate the prognostic nomograms for both OS and CSS in patients with FS. We developed comprehensive nomograms for 3-year and 5-year overall survival and cancer-specific survival on the basis of 663 cases extracted from the SEER database.
Our results showed that the following independent prognostic factors could influence the survival of patients with FS were age, sex, surgery, tumor stage, pathologic grade and tumor size. The result of OS prediction by nomogram showed that age was the main factor affecting prognosis. It was widely believed that age was related to the survival outcome of various cancers (Eggener SE et al., 2011; Eguchi T et al., 2017; Wensink MJ et al., 2016; Adam MA et al., 2016). The correlation between age and OS might be partly due to our use of all-cause mortality rather than cancer-specific survival. In other words, older patients usually had chronic diseases or postoperative complications that made them more likely to die.
Although it appears that a larger tumor predicts a poor prognosis, it is necessary to conduct further studies to examine this. In previous studies, the effect of tumor size on survival was inconsistent. Most of these studies believed that larger tumors size was harmful to patient survival (Hesla AC et al., 2016; Park JT et al., 2015; Raciborska A et al., 2014; Wan Z-H et al., 2018). In contrast, other studies supported that tumor size had no influence on the survival (Gayner SM et al., 1997; Yock TI et al., 2006; Donati D et al., 2007). Regard our article, the result indicated that tumor size was the most important factor affecting CSS. One possible explanation for these findings was that tumor size during diagnosis was related to the treatment used, which might affect survival.
Multivariate COX regression analysis showed that sex, surgery, tumor stage, pathologic grade were also independent prognostic indicators for FS patients. Gender was also an important variable related to the prognosis of patients with cancer. In our article, the survival rates of male FS patients were worse than that of female patients. Our study also showed that surgical treatment was related to a better prognosis. Tumor stage was also an independent prognostic factor. The presence of distant stage resulted with a lower survival rate than localized or regional stage. This trend further demonstrated the importance of improving early diagnosis. In addition, pathologic grade could reflect the biological behavior of malignant tumors, which associated with the occurrence of distant metastasis and worsened the prognosis of survival outcome.
This study was based on data extracted from the SEER database, which had a large sample size and sufficient cancer data. However, our research had some limitations. As a retrospective study, the findings may be needed to further validate by randomized controlled trials and prospective study. Some clinical pathological parameters, such as comorbidities, vascular infiltration, surgical margin status, chemotherapy or other treatment were not available in the SEER database, so we did not include these factors in the nomogram (Okamoto M et al., 2018; Grünwald V et al., 2016; Stevenson JD et al., 2018; Zagars GK et al., 2003). Finally, the C-index is a good nomogram verification tool, but it is more reliable if you use other independent large-scale data sets for external verification.